The present invention relates to a non-sliding vacuum gate valve, and more particularly to an improvement for reducing the number of components, and for attaining smooth action, simple structure and small size without using a spring member that forces a valve rod in a predetermined direction.
A structure of such a non-sliding vacuum gate valve used in the prior art is disclosed in Unexamined Japanese Patent Publication No. 7-83336, for example. The valve uses a set of inclined link and tension spring, a set of plate cam and tension spring, or a set of pin and cam hole, so as to prevent slant movement of a valve plate and a valve rod when they are moving, and so that the valve plate and the valve rod are slanted after they have reached a predetermined position to close the opening of a valve box by the valve plate.
However, a conventional non-sliding vacuum gate valve as mentioned above has following disadvantages. First, the conventional valve has a complicated structure since it requires a lot of components and a space for receiving the tension spring.
In addition, it is desirable for spring to be strong for secure action. In this case, reaction of the tension spring is strong, so that a high power cylinder is needed.
Furthermore, in order to activate a mechanical lock, the cam plate or link should be in the horizontal position. However, it is difficult to start the opening action from this position, resulting in little possibility of a mechanical lock being used.